This invention relates to the art of edge location sensing, and more particularly to a new and improved edge sensing method and apparatus employing acoustic energy.
One area of use of the present invention is in material handling where it is desired to sense the edge of a web of material passing along a surface, although the principles of the invention can be variously applied. An example is sensing or measuring the edge of a paper or film web as it is passing a roller surface. Prior art arrangements exist which utilize transmitted energy such as light or ultrasonic energy to measure one or more dimensions of a workpiece such as sheet material. Such arrangements often are complex and typically provide transmitting and receiving or detecting components on opposite sides of the sheet of material which intercepts the energy beams between the components.
It would, therefore, be highly desirable to provide a new and improved web edge sensing method and apparatus which is relatively simple in structure and operation, which operates at relatively low energy levels and which provides relatively high resolution.